These games used the GoldSrc engine. Any game built on this engine gets called a mod. But this is not what most people actually think of when people are talking about mods. Rust is not a mod of Unity. These are game engines that people built a game using.
>DotA
This was a custom map. Not a mod.
>LoL, HoN
These were built on in house game engines and were not a mod.
>PUBG
This game used UE4 and was not a mod.
edit:
https://developer.valvesoftware.com/wiki/Counter-Strike#Vers...
Also custom maps are mods by definitions anyways, with the exception of games where the creation of maps is a component of gameplay.
Or, if you were slightly older, you might call them UMS, as they were in Starcraft. Short for "Use Map Settings", indicating that the game logic should come from the scripts and triggers in the map file rather than the built-in logic for ladder games.
This is even better. Because it's a map you can start it without modifying your game installation.
There were "real" WC3 mods, but it was always cumbersome and worked reliably only in singleplayer.
Gameplay-wise it's a mod obviously.